1. Field of the Invention
The present invention relates to an image processing technique for use in realizing natural representation of images in computer graphics with less processing load, in which the images may be a person, an animal, a vehicle such as an automotive or an airplane, or an object that moves on a complex ground or a huge object whose shape is changing, in a virtual 3D space.
2. Description of the Related Art
A recent advancement in computer graphics technique allows more natural representation of 3D images than before. Computer graphics are used in various fields. Computer games are one of typical examples where the computer graphics are used.
Some computer games, such as so-called action adventure games, are designed in a virtual 3D space in which a character object or objects can be moved by a user. In such computer games, a real-time response to the user's input is preferred to provide a character object that behaves or moves in a natural manner. The character object is an image of, for example, a person, an animal, a vehicle such as an automotive or an airplane, or a predetermined object.
In such computer games, the character object comes into contact with various objects that are provided in the virtual 3D space. The object with which the character object contacts has a fixed shape or a changing shape. The former may be, for example, a ground or a cliff while the latter may be a huge creature such as a monster.
When the character object moves on the ground, the location and orientation of the character object are changed according to the shape (surface texture) of the ground. Japanese Patent Laid-Open Nos. 6-277362 and 2003-44878 disclose inventions relating to an image processing when the character object moves along the ground surface.
In Japanese Patent Laid-Open No. 6-277362, there is disclosed a 3D gaming device with which the topographic shape of the ground in the virtual 3D space is considered and reflected to the location and orientation of the character object. In this 3D gaming device, topographic information of a game field is stored and this topographic information is used to change object information of a moving object (character object). By using the object information that has been changed, the image of the character object is created with the topographic information taken into account. In Japanese Patent Laid-Open No. 2003-44878, there is disclosed an image generation system which provides natural behaviors of a model object (character object) with less processing load. The shape of the model object is changed depending on the topographic shape of the ground in order to prevent a part object (such as limbs of a model object) from being hidden by the ground surface.
On the other hand, when the character object moves on an object whose shape is changing, the location and orientation of the character object should be changed immediately according to the change in shape of the object. However, such image processing requires high processing load. There is a limit to provide a real-time result. Accordingly, conventional techniques rely on reproduction of video images that have been previously generated to move the character object on a changing object.
In Japanese Patent Laid-Open Nos. 6-277362 and 2003-44878, only the character objects that are moved on an object whose shape is fixed is taken into account. However, depending on the scenario of a game, the character object may be moved on a moving object such as a huge creature. The techniques disclosed in Japanese Patent Laid-Open Nos. 6-277362 and 2003-44878, however, do not consider movement on a moving object as described above. In addition, when video images are reproduced to provide an object whose shape is changed, the character object is limited in movement, so that the user's input cannot be reflected perfectly.
A major purpose of the present invention is to provide an image processor with which images can be obtained wherein a character object is moved in a natural manner according to the user's intent, regardless of any change in shape of an object, while taken the above into consideration.